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24 Electrical Spacings
( z& E v$ \. ?. H" T6 d% q24.1 The spacing between uninsulated live parts of opposite polarity, and between uninsulated live parts
7 D1 {4 V, J+ r, {and metal that is capable of being grounded shall not be less than 1/4 inch (6.4 mm) through air or 3/8
6 J) m4 V: Z; {2 b& o5 Dinch (9.5 mm) over surface. The outer wrap of an open core and coil ballast is determined to be an! K6 M1 f2 ~+ j" e
uninsulated live part with respect to this requirement.
B9 S3 X" d' A# o) sException No. 1: The spacing requirements do not apply between uninsulated live parts of a wiring device,
- x i. W2 S+ K3 osuch as a lampholder or switch, and dead metal that is part of the wiring device and including mounting
- m2 q. V' a: ~0 lscrews, rivets, yoke, clamp, or similar components; or for a portable luminaire provided with a grounding
# s+ X0 A+ R. R9 P6 omeans between such live parts and that part of the dead metal surface of the portable luminaire on which. I8 c: i, s( c) T5 f' m' q
the device is mounted in its intended manner. See Figure 24.1.6 X( l- N1 C- a
Exception No. 2: When an isolated dead metal part is interposed between or is in close proximity to:
) F7 `: ^" ^/ ka) Live parts of opposite polarity;
; w, @2 \6 o3 V/ e" t# h8 K Yb) A live part and an exposed dead metal part; or
7 z o! ~* o2 B: f" Pc) A live part and a dead metal part that is able to be grounded, the spacing shall not be less" h! F( m; T( c" W3 g5 g
than 3/64 inch (1.2 mm) between the isolated dead metal part and any one of the other parts8 o7 V. I9 v5 {7 x
previously mentioned, provided the total spacing between the isolated dead metal part and the
$ {9 _: L: I, C. U% {, ~two other parts is not less than 1/4 inch (6.4 mm) through air or 3/8 inch (9.5 mm) over surface.
3 p% Y+ p8 J1 Z. B% j5 `/ Y7 xException No. 3: The spacing between uninsulated live parts of a Class 2 circuit and between such parts
2 `( ]4 e" K# ^; s |0 `% K$ Gand dead metal that is grounded in service is not specified.4 k& H9 p$ q1 U& v2 @$ p: A6 V. O1 t
! K Z" O) |4 m, K6 ^2 s9 o3 J
各位大侠,UL153这章的dead metal part,是不是可以直接理解为非金属部件?
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